1. Field of the Invention
This invention relates to releasable fastening arrangements and more particularly it concerns a novel releasable fastening assembly and fastener element for temporarily but securely attaching plastic wafers to articles of merchandise.
2. Description of the Prior Art
The present invention is particularly useful with electronic theft detection systems for releasably fastening plastic wafers, which encase electronic target circuits, to articles of merchandise, Examples of such electronic theft detection systems, wafers and target circutis are shown and described in U.S. Pat. No. 3,500,373 and No. 4,321,586. As there shown, plastic wafers, in which electronic target circuits are embedded, are releasably attached to articles of merchandise by means of tack-like fastener elements having a large expansive head and a thin elongated pointed shank securely attached to and extending out from the head. The shank passes through the article of merchandise and through the wafer and into a releasable locking mechanism which is either integral with or separate from the wafer. The shank is configured to permit the locking mechanism to grip the side of the shank positively in the locked condition but to allow the shank to be withdrawn when the locking mechanism is in its released condition. The locking mechanism may be a ball and clutch type mechanism as shown and described in U.S. Pat. No. 3,911,534 (now disclaimed); and the shank of the fastener element, in order to provide workable locking interaction with the ball and clutch mechanism, is formed with circular grooves, as shown in U.S. Pat. No. 4,299,040.
When an electronic theft detection system is in operation and protecting merchandise, as in a store, the plastic wafers are attached to the articles of merchandise by means of the tack-like fastener elements and locking mechanisms so that they cannot be removed except by an authorized person, such as a sales clerk, with a special lock release device at a counter or checkout station. If the protected article is carried out from the store or protected area, it must pass near monitoring antennas; and if the wafer is still attached to the article, the electronic circuit embedded in the wafer will interact with an electromagnetic field in the vicinity of the antennas and cause a characteristic disturbance of that field that will be detected and will cause an alarm to sound. When, however, a legitimate purchase is made, the clerk or salesperson uses the special lock release device to release the lock and withdraw the tack-like fastener element so that the wafer can be removed from the article and the article can then be carried out past the interrogation antennas without activating the alarm.
It will be appreciated that in a busy store a very large number of these tack-like fastener elements are removed from locking mechanisms in a short period of time. Often, because of the haste involved in these operations, the fastener elements will fall on the floor and it may not be convenient to pick them up at once. If these fastener elements fall with their sharply pointed shanks extending upwardly, they can present a hazard to workers and others in the area. It is to this problem that the present invention is directed.
It is known in the prior art to form tacks or nails with heads of various different configurations for decorative purpose and it is also known that such different decorative configurations include upholstery nails with conical heads. However, those nails are not designed to be released from locking mechanisms and the problem of dropping, as described above, is not so prevalant with those nails, because they are used only once and are not unlocked for repeated use as are the fastener elements of this invention.